A per-P(l)EX-ing situation Wenatchee and East Wenatchee Home Inspections

The world of domestic water supply piping was destined to change when an English chemical company produced the first polyethylene plastic (PE) in 1933.

In 1968 a German inventor, Thomas Engel, developed a method that chemically cross link the molecules in PE. This produces a plastic that was stronger and more tolerant of high temperatures than standard polyethylene. Thus the X was added to PE to become PEX.

Now we have three types of PEX; PEX-A (Engel method), PEX-B (Saline Method) and PEX-C (irradiation method). PEX-A is the most flexible version of this material.

The PEX-A Engel (peroxide) cross-linking method relies on peroxide being mixed with HDPE (high density polyethylene) and fed into the extruder under high pressure. The product is then passed through a long heated die where the cross linking takes place, caused by a chemical reaction between the peroxide and the polyethylene at a high temperature.

The PEX-B Sioplas (saline) cross-linking process was patented in 1968, followed by the Monosil (saline) process in 1974 and the Vinyl-saline copolymers in 1986. The difference in these methods is primarily in the way that the vinyl-saline and catalyst are added to polyethylene before it goes through the extruder. While some of the cross linking occurs in the extruder, the majority actually takes place in a water bath or in a sauna at elevated temperatures, after the tube passes through the extruder.

The PEX-C Electron beam (irradiation) method was made feasible in the mid-1970s. Of the three processes, the electron beam requires a substantially greater initial investment in tooling and machinery, costing millions of dollars. No chemicals are added or used in the cross-linking process; cross linking is accomplished after the tube has been extruded, coiled and placed in a special electron beam "oven."

From my polling, PEX-A seems to be the preferred PEX by plumbers. There are some great advantages to this material (PEX). It is easy to run, you can create better sweeps/bends and if very flexible. It is highly resistant to bursting in cold weather. It can be set up on a manifold system very easily to create more even pressure throughout the home.

There is still some question on how will react with oxidizers (chlorine and fluorine) over long periods of time. Some manufacturers include stabilizer additives in the basic polymer formulation to sacrificially react with those oxidation agents.

PEX is fast becoming the plumbing standard in modern construction. (It has been used in Europe for many years now). Before then it was mostly used in radiant systems.

PEX tubing cannot be used in applications exposed to sunlight, as it degrades fairly rapidly. Leaving it exposed to direct sunlight for as little as 30 days may result in premature failure of the tubing.

Wenatchee and East Wenatchee Home Inspections- Per-P(l)EX-ing situation

NCW Home Inspections, LLC  is located in Wenatchee Washington serving Chelan County, Douglas County, Okanogan County and Grant County Washington.                                      

NCW Home Inspections LLC-509-670-9572